SUMMARY/ABSTRACT This NIH S10 High-End Instrumentation grant application requests funds to purchase a SIEMENS Next Generation PET/CT scanner. The SIEMENS Next Generation PET/CT scanner which we intend to purchase with this grant will be the only commercially available long-bore 8-ring PET/CT system with SiPM detectors; this scanner will replace our much-used current research PET/CT scanner, a 10-year-old SIEMENS Biograph 40 PET/CT scanner housed in our 8,900 square foot Washington University Center for Clinical Imaging Research (CCIR). Washington University has a long history of expertise in PET imaging. Creating the foundation for expertise in PET, Washington University's research in imaging sciences dates back to physicist and Nobel laureate Arthur Holly Compton's discovery of gamma ray/electron scattering interactions in 1922. This ground-breaking research continued with the installation of a cyclotron in 1938, the first in the world for biomedical applications. In the early 1960s another biomedical cyclotron was used to produce short-lived isotopes of oxygen (15O) and carbon (11C). This dovetailed with the development of the first human/clinical use positron emission tomography (PET) scanner by Michel Ter-Pogossian and team at WU in the mid 1970s. It is especially important for universities performing basic high-impact PET research and first-in-human radiotracer studies, and participating in large-scale single center and multicenter PET/CT trials to have the most advanced PET/CT equipment available. Currently, Washington University (WU), despite 69 PET/CT basic science studies and clinical research trials, multiple first-in-human studies and 4 functional cyclotrons, does not have a research PET/CT system with TOF and optimal count rate performance required for the better image quality and sensitivity needed to detect subtle findings and improve quantitative accuracy in small lesion tracer uptake measurements. The Next Generation PET/CT scanner will be installed in the CCIR, a Mallinckrodt Institute of Radiology, Washington University clinical research NIH recharge facility locate centrally in the main teaching hospital of the Washington University School of Medicine. The CCIR provides a substantive support system for its users, 70% of whom are non-radiologists. The director of this facility, Pamela Woodard, M.D., is the PI of this grant. As Sr. Vice Chair for Radiology Research Facilities, she also oversees other facilities (with their own directors) supportive of this instrument, including the Cyclotron Facility.